Synchronous Optical Networking (SONET) is a standard way to multiplex high-speed traffic from multiple vendors' multiplexers onto fiber optic cabling. SONET equipment and software enable network providers to carry traffic from many types of customer equipment in a uniform way on backbone fiber optic cabling.
SONET is slightly different in the long haul space compared to the metro space. The long haul space is [please fill in the blank with a brief description of the long haul space]. The metro space is [please fill in the blank with a brief description of the metro space]. SONET for the metro space provides additional functionality for other protocols, such as Gigabit Ethernet, ESCON, FIBERCON, Fiber Channel 2X, and HDTV, to name a few.
Service providers provide services to various customers by provisioning a line card for the customer. Line cards handle one of a several standard rates. TABLE 1 identifies a list of different rates. In order to provide customers with different data rates, service providers install different line cards, wherein each line card handles a different data rate. In cases where a service provider has many customers, it is likely that the service provider has many line cards to accommodate the different user requirements. However, in cases where a service provider has fewer customers, it is likely that the service provider will need to purchase a new line card to accommodate a new customer with different rate requirements.
TABLE 1OpticalElectricalLine RatePayloadOverheadLevelLevel(Mbps)Rate (Mbps)Rate (Mbps)OC-1 STS-1 51.84050.1121.728OC-3 STS-3 155.520150.3365.184OC-9 STS-9 466.560451.00815.552OC-12STS-12622.080601.34420.736OC-18STS-18933.120902.01631.104OC-24STS-241244.1601202.68841.472OC-36STS-361866.2401804.03262.208OC-48STS-482488.3202405.37682.944
In order to provide different data rates from the same infrastructure, reference clock signals with different frequencies are needed. One possible solution is to use a single voltage controlled oscillator with a wide range of possible frequencies.
Although the particular frequency can be provided by application of an appropriate control voltage to a voltage controlled oscillator with a wide range of possible frequencies, such oscillators are difficult to control. Voltage controlled oscillators with a wide range of possible frequencies are very sensitive to changes in the control voltage. Therefore, such oscillators tend to be less stable and more susceptible to jitter.
Further limitations and disadvantages of connection and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with embodiments of the present invention as set forth in the remainder of the present application.